1. Field of the Invention
The present invention relates to a novel organic photoconductive material and a photosensitive material for electronic photography using it. More particularly, the present invention relates to an organic photoconductive material comprising a specific azo compound and a novel photosensitive material for electronic photography comprising a photosensitive layer containing it.
2. Description of the Related Art
Recently, electronic photography has been adopted not only in the field of photocopier but also widely in the fields where photographic technology has been used, such as printing form plates, slide films, microfilms and the like. Application to high speed printing using RASER, LED or CRT as the light source is also being developed. Application of electronic photosensitive materials to fields other than the photosensitive materials for electronic photography, such as electrostatic recording elements, sensor materials and the like, is also a subject of recent studies. Therefore, requirements for electronic photoconductive materials and photosensitive materials for electronic photography using them are becoming higher in degree and wider in range.
Materials comprising a photosensitive layer containing an inorganic photoconductive material, such as amorphous selenium, cadmium sulfide, zinc oxide and the like, as the main component thereof have been used mainly as the photosensitive material for electronic photography. Even though the photoconductive materials using inorganic materials are useful, they are not always satisfactory with respect of sensitivity, heat stability, moisture resistance and durability. Particularly, they have problems on handling during production because of toxicity of amorphous selenium and cadmium sulfide.
Photosensitive materials for electronic photography using various kinds of organic photoconductive materials have been proposed and adopted in practical applications as materials having no such problems. Obviously, a photosensitive material for electronic photography is required to have the function of carrier generation and the function of carrier transportation. Various kinds of organic pigments, such as phthalocyanine pigments, multi-ring quinone pigments, indigo pigments, dioxadine pigments, quinacridone pigments, azo pigments and the like, have been proposed as organic materials used as the carrier generating substance but only limited kinds of them have been practically applied. Only limited kinds of the carrier transporting substance have also been practically applied. Therefore, it is the actual situation of the present time that a photoconductive material which can sufficiently satisfy the wide requirements of electronic photographic processes, not to mention those of newer applications other than electronic photography, have not been obtained.